FI73445B - FENOLFORMALDEHYDRESOLER FOER FRAMSTAELLNING AV FENOLSKUM. - Google Patents

Description

Phenol formaldehyde resoles for the preparation of phenolic foams. - Phenolformaldehyde resoler for the production of phenolskum.

1 73445

The present invention relates to certain aqueous phenol-formaldehyde resoles prepared by condensing β-enol and formaldehyde catalyzed by a base. These phenolic resoles are particularly useful in the preparation of phenolic foams having both low k values and excellent refractory properties, excellent compressive strength, density, friability and other properties required for an insulating sheet. The invention also relates to foamable phenolic resole compositions prepared using aqueous phenolic resoles and phenolic foams made from the compositions.

Phenolic foams made from phenol formaldehyde resoles have been known for several years. The general opinion is that of all known foam insulators, phenolic foams have the best fire resistance value. Phenolic foams do not burn even when they are brought into contact with the flame of a blower lamp and release minimal amounts of toxic gases. Phenolic foams can withstand temperatures of 190 ° C without decomposition. In the ASTM E-84 test, phenolic foams have a Steiner Tunnel Flame Spread Rating of about 5, a Fuel Contribution of about 0, and a Smoke Rating of about 5.

Despite these advantages and the generally advantageous economy, phenolic foams have not previously penetrated the thermal insulation market. One of the main reasons why phenolic foams have not been successful is that the phenolic foams produced so far have had an unsatisfactory initial thermal conductivity value or have increased in thermal conductivity over time. In addition, the compressive strength of phenolic foams in the prior art has not been as high as is desirable for normal handling. In addition, it has been reported that prior art phenolic foams have experienced severe problems with brittleness and spoilage.

The general mixture of phenolic foam and its production method are generally known. The foamable phenolic resole mixture is prepared by mixing together aqueous phenol-formaldehyde resole, a blowing agent, a surfactant, optional additives, and an acidic curing agent into a substantially uniform mixture. The curing catalyst is added in such an amount that a curing reaction, which is highly exothermic, is initiated. The heat of the curing reaction evaporates and expands the blowing agent, causing the mixture to foam. The flotation process is best performed in a closed mold.

The continuous manufacturing method of the insulation sheet of phenolic foam is as follows. The foamable phenolic resolution mixture is prepared by continuously feeding an aqueous phenol-formaldehyde resole, blowing agent, surfactant, optional additives and acidic curing catalyst to a suitable mixing device. The ratio of these ingredients varies depending on the desired density, thickness, etc. of the finished product. The mixing device combines these ingredients into a substantially uniform mixture which is continuously applied evenly over a moving substrate, usually a protective coating such as cardboard which adheres to the foam. The foam mixture is usually covered with another protective coating, such as cardboard, which adheres to the phenolic foam. The coated foam mixture is then passed to a double-belt press-type device in which the heat generated during curing still evaporates and expands the blowing agent, whereby the mixture foams as it cures.

As mentioned above, one of the main disadvantages of previous phenolic foams is the unsatisfactory initial value (k-value) of 3 73445 thermal conductivity. One of the main reasons for the poor initial thermal conductivity of phenolic foam is believed to be the breakage of the cell walls during the initial foaming and curing of the foamed phenolic resole mixture. As a result of this outbreak, the blowing agent immediately disappears, causing a poor initial value of thermal conductivity. The ruptured cell walls also easily allow water to foam, further increasing thermal conductivity. The ruptured cell walls are believed to adversely affect the compressive strength and other properties of the phenolic foam. Another major reason for the poor initial thermal conductivity of phenolic foams is the loss of blowing agent before the cell walls have formed sufficiently and trapped the blowing agent.

In this connection, it has already been mentioned that another disadvantage of the prior art phenolic foam is the undesired increase in thermal conductivity over time (slipping of the k-value). Even in prior art phenolic foams with non-ruptured cell walls that have encapsulated the blowing agent, the foams tend to lose the blowing agent over time, with a corresponding increase in thermal conductivity. There are believed to be two main reasons for the increase in thermal conductivity over time. The first is that the cell walls and bridges formed when the cell walls join together have small openings or needle holes. Over time, the blowing agent may diffuse through these small openings and be replaced by air. This slow replacement of the blowing agent with air increases the thermal conductivity and lowers the thermal insulation value. Through these small openings, the phenolic foam can also absorb water, which further increases the thermal conductivity. These openings are believed to be due to the water present in some parts of the phenolic resole mixture to be foamed, especially the catalyst. At the same time, our pending application relates to a method of avoiding gaps in cell walls and bridges by using certain anhydrous arylsulfonic acid catalysts.

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Another major cause of loss of thermal conductivity over time is cracking of cell walls. In many prior art phenolic foams, the cell walls are very thin.

When phenolic foams with thin walls are exposed to high temperatures, the cell walls dry and crack. Thermal insulation is also quite often subjected to heating and cooling cycles, with expansion and contraction, respectively. The expansion and contraction of the thin cell walls also causes cracking. Cracking of thin cell walls allows the blowing agent to leak over time, increasing thermal conductivity and deteriorating thermal insulation.

Several methods have been proposed in the art to solve the thermal conductivity problem. For example, one method involves a two-step process in which the phenolic resole mixture to be foamed is first foamed under vacuum and then cured at high temperatures and low pressures. This method actually results in a foam with an abundance of cell walls that have not ruptured; however, there are still many cell walls involved that are either ruptured or that are thin and easily cracked under thermal stress. This method is also not commercially desirable due to the equipment required and the longer time required. In the second method, the foamable phenolic resole is foamed and cured at low temperatures, (i.e., below 66 ° C). This method also reduces the number of bursting cell walls, but the resulting phenolic foam still has thin cell walls. A co-pending application by the same applicant relates to a method for clothing a phenolic resin mixture to be foamed and a hardener by holding the flotation and curing mixture under pressure. This method greatly reduces the number of ruptured cell walls, but the resulting phenolic foam may still have a significant number of ruptured cell walls or may have lost swelling agent before the cell walls were cured, 5,734,45, and in addition, the cell walls may be thin.

Other attempts to improve the thermal conductivity of phenolic foams have relied in particular on the development of modified phenolic resoles or surfactants or the use of certain additives in a foamable phenolic resole. None of these methods have been commercially successful.

See, e.g., D 'Allesandro · U.S. Patent 3,399,094, Buncklark et al .: U.S. Patent 3,821,337, Moss et al .: U.S. Patent 3,968,300, Moss: U.S. Patent 3,876,620, Papa: U.S. Pat. U.S. Patent 4,033,910 to Beale et al., U.S. Patent 4,133,931, Bruning et al .: U.S. Patent 3,885,010, and Gusmer, U.S. Patent 4,303,758.

According to the present invention, it has been found that the rupture of cell walls during foaming, the disappearance of the blowing agent before the cell walls have formed sufficiently and retained the blowing agent, and the formation of thin cell walls is directly related to the phenolic resole used in the production of phenolic foam.

It is therefore an object of the present invention to provide an improved aqueous phenolic resol which provides a phenolic foam whose cell walls are substantially free of perforations.

It is a further object of the present invention to provide an improved aqueous phenolic resol which provides a phenolic foam which does not lose the blowing agent until the cell walls are formed so as to retain the blowing agent.

It is a further object of the present invention to provide an aqueous phenolic resole which provides phenolic foams whose cell walls do not crack due to drying or swelling and contraction.

Other objects and advantages of the present invention will be apparent to those skilled in the art from the following description and drawings.

The present invention relates to an aqueous phenol-formaldehyde resole useful in the preparation of a phenolic foam insulation having good thermal insulation properties, compressive strength, density, brittleness and other properties required for commercial application. The aqueous phenol-formaldehyde resole is a substantially phenol-formaldehyde condensation polymer having a molar ratio of formaldehyde to phenol of about 1.7: 1 to about 2.3: 1, preferably about 1.75: 1 to about 2.25: 1, and most preferably about 2 : 1. Phenoliser resol has an average (weight) molecular weight as determined by gel permeation chromatography (GPC) of at least about 800 and most preferably from about 950 to 1500. Resol also has an average (number) molecular weight as determined by GPC chromatography of at least about 350 and most preferably about 400 and a dispersibility greater than about 1 , 7, preferably about 1.8 to 2.6. Phenol formaldehyde resins with these properties can be processed in a consistent and reproducible manner into phenolic foams with initial k-values of 0.10 to 0.13, compressive strengths of 1.4 to 2.5 kp / cm and densities of 24 to 80 kg / m 2. The foam also has excellent t ui en kes t oa r vot.

An improved aqueous phenol-formaldehyde resole can be prepared using any standard method known for the preparation of aqueous phenolic resoles.

The preferred process for the preparation of aqueous phenolic resoles reacts a highly concentrated aqueous phenol (greater than 88% by weight) with highly concentrated formaldehyde (greater than 85% by weight) in the presence of an alkaline catalyst at a slightly higher concentration than is commonly used in the preparation of phenolic resoles. In the preferred process, formaldehyde is added to the mixture of phenol and alkaline catalyst very or continuously during the first part of the condensation reaction.

u 7,73445 These improved aqueous phenol formaldehyde resosols are formulated as foamable phenolic reso mixtures which, in addition to the aqueous phenolic resole, contain a surfactant, a blowing agent, optional additives and an acidic foaming and curing catholyte. The phenolic foams to be foamed give a phenolic foam with better properties, in particular thermal insulation properties, compared to previous phenolic foams in the art.

In the following drawings, the same numbers denote the words parts.

Figures 1A and 1B schematically and in partial section illustrate substantially closed molds used to make phenolic foam in the laboratory.

Figure 2 is a schematic side and sectional view of a double-belt device for the continuous production of phenolic foam.

Fig. 3 schematically shows a section along the line III-III in Fig. 2.

Fig. 4 schematically shows a section along the line IV-IV in Fig. 3.

Fig. 5 schematically shows a section along the line V-V in Fig. 3.

Figures 6-22 are scanning electron photomicrograps (SEM) images showing the cells and cell walls of phenolic foams. These phenolic foams were made using typical resoles of the present invention. All SEM images are 400x magnification unless otherwise noted.

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It was mentioned above that the use of phenolic foams in thermal insulation, especially in ceilings, walls and pipes, is particularly desirable due to the excellent refractory properties inherent in phenolic foams. However, phenolic foams have so far been known to suffer from generally too poor initial k-values and their inability to maintain a low k-value over time. The thermal insulation capacity of a foamed material can generally be assessed by thermal conductivity or k-value. The thermal conductivity, or k-value, of a particular insulating material is measured by ASTM method C-518 (Revised). Typically, its dimension is BTU / inch / hour / square foot / ° F. The lower the k-value, the better the insulation capacity of the material. In addition, the longer the foam maintains a low k value, the better the insulation performance of the material.

By low k-value is meant a k-value that is substantially less than about 0.22, which is approximately the k-value of air. By low initial k-value is meant a k-value that is substantially less than 0.22 measured after the prepared foam has reached water equilibrium, usually within about 5 days. Using the phenolic resoles of this invention, it has been found that it is possible to produce a phenolic foam whose k-values decrease during the first few days as the water content of the phenolic foam equilibrates with the environment. Thereafter, the k-value remains substantially constant over time. The resoles of this invention can be used to prepare phenolic foams having kTM initial values of less than 0.15 and generally between 0.10 and 0.13 as measured by the ASTM method. Some foams prepared using the preferred phenolic resoles had k-values less than 0.10 as measured at very low water contents. It is possible to produce a phenolic foam that maintains these low k values over time.

The total densities of the phenolic foams made from the phenolic resoles of the invention (including the shell of the foam li 9 73445) are generally between about 24 to about Θ0 kg / m 2 and most preferably between about 32 to about 64 kg / m 2 and the core densities (i.e. without foam shell). from about 24 to about 72 kg / m 3, and preferably from about 32 to about 65 kg / m 2 ". It is possible to produce phenolic foams which are substantially closed-cell foams (i.e., substantially free of ruptured cell walls) and generally contain at least 90 - 95% closed cells and typically more than 95% closed cells as measured, for example, by an air pycnometer using the ASTM method D-2865-70 (1976).

The k-value of the phenolic foam is directly related to the ability of the phenolic resole mixture to be foamed to capture the blowing agent during the flotation and curing steps and retain the swelling time over time. The thermal conductivity of phenolic foam is directly related to the thermal conductivity of the entrapped gas. For a phenolic foam with only air left, the k-value can be expected to be about 0.22. A phenolic foam with fluorocarbon retained can be assumed to have a k-value close to the thermal conductivity of the entrapped fluorocarbon. Commercial fluorocarbons have k-values of about 0.10. The excellent phenolic foam thus has a k-value of about 0.10 and maintains this k-value over time. Phenolic foams made from the resoles of this invention have such a k-value that can be maintained over time.

It has been mentioned above that the poor initial k-value of the prior art phenolic foam is believed to be due to two main reasons. Another reason is the disappearance of the blowing agent before the cell walls have become so strong that they trap the blowing agent. Another reason is cell wall eruptions during flotation. As mentioned above, it is believed that the loss of thermal insulation over time is due to a number of small openings in the cell walls and the cracking of the thin cell walls by thermal stress.

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The main cause of cell wall rupture is the pressure exerted by the expanding blowing agent during the formation of the phenolic foam. At temperatures normally used in the commercial production of phenolic foams (i.e. 52-121 ° C), the pressure exerted by the blowing agent during foaming and curing is higher than what the cell walls can withstand, especially in the initial stage of foaming and curing. The cell walls of phenolic foams made with prior art resoles cannot withstand very high pressure until foaming has been completed and substantial curing has taken place. The expandable blowing agent thus punctures the walls before they have hardened sufficiently to give an open-celled foam with unsatisfactory thermal conductivity. A co-pending patent application discloses a method for preventing the rupture of cell walls during flotation and curing. In this method, the surfaces of the phenolic resole mixtures to be foamed are kept under pressure during foaming and curing.

Another cause of cell wall rupture is the presence of water in the foamable phenolic resolution mixture, especially water in the catalyst system. The water-induced cell wall eruption is nowhere near as strong as the eruption due to the foam mixture not being counteracted by at least as much force as the expanding blowing agent, or the eruption due to the use of a phenolic resole that generates heat too quickly and too much. Another co-pending patent application discloses a method for preventing or inhibiting water-induced cell wall rupture. This process uses certain anhydrous arylsulfonic acids as the flotation and curing catalyst. Although these methods help prevent cell wall rupture, they do not prevent all cell wall rupture. When a special phenolic resol of the present invention is used, a phenolic foam can be prepared in which no

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11 73445 essentially no erupted so 1use in am.

The disappearance of the blowing agent before the cell walls have become so strong that they retain the expanding blowing agent is due to two interdependent factors. First, prior art resolutions are highly reactive. When such large amounts of acidic curing agent are added to these resoles that it is sufficient to foam and cure the resole in a reasonable amount of time, these resoles generate heat very rapidly and the heat peaks rise substantially above 93 ° C. This rapid and high generation of exothermic heat drives away most of the blowing agent until the cell walls are sufficiently formed and capable of trapping the blowing agent. The result is a phenolic foam with only a small amount of blowing agent left in the cells. In addition, rapid and high heat generation also tends to puncture cell walls even in the presence of counterforce. Second, prior art aqueous resoles in the art have low viscosity bonding properties, especially when formulated as foamable mixtures with surfactants, blowing agents and acid catalysts. Because the temperature of the mixture to be foamed rises rapidly in the early stages of flotation, the viscosity of the resole decreases sharply and does not increase until substantial crosslinking of the resole occurs. Cell walls formed of low viscosity resin are unable to capture and retain the blowing agent until substantial curing has occurred. Thus, much of the blowing agent disappears before the cell walls are strong enough to produce a phenolic foam with little or no blowing agent left in it.

The formation of cell walls that are very thin and crack under thermal stress is also due to resoles that have too rapid and high heat generation and too low viscosity. It was mentioned above that the temperature of the mixture to be foamed rises in the early stages of the flotation and curing reactions, with the viscosity of the phenolic resin decreasing or at least not increasing significantly before significant crosslinking occurs. Until the viscosity of the phenolic resin increases significantly, the phenolic resin11a which forms the cell walls tends to drain during this time.

Drainage involves a gradual thinning of the cell walls and a thickening of the bridges between the cells. If too much leakage occurs before the resole forming the cell walls is sufficiently cross-linked, the resulting cell walls are very thin. In addition, thin cell walls easily rupture and crack very easily due to high temperature, drying, or normal expansion and contraction.

The aqueous phenolic resole of the present invention is superior to previous phenolic resoles. It is well known in the art to catalyze the condensation of phenol and formaldehyde in aqueous solutions with the aid of a base to form aqueous condensates, commonly referred to as resoles. As discussed herein and well known in the art, aqueous phenolic resoles readily cure to higher molecular weight, crosslinked disposable resins. The crosslinking curing reaction is highly exothermic and greatly accelerated by acidic substances. Prior art resols can be formulated with blowing agents, surfactants, and acid curing catalyst and optional additives into a foamable mixture that can be foamed and cured to a phenolic foam. However, prior art resoles generally have two disadvantages; their exothermic heat generation is too high and too fast and they have too low a viscosity. First, prior art resoles, when used in such an amount of acidic catalyst as is sufficient to foam and cure the mixture in a reasonable amount of time, generate too much and too much heat. As a result, either the cell walls of the resulting foam burst under too high a pressure or the blowing agent flows away before the cell walls are so strong that they trap the blowing agent. In either case, a phenolic foam with a poor initial k-value is obtained. Second, the viscosity of prior art resoles is too low, especially when formulated into foamable mixtures. The low viscosity allows the blowing agent to escape before the cell walls are so strong that they trap the blowing agent, and the phenolic resole flows out of the cell wall as they form, resulting in very thin cell walls that crack during normal use. This also results in a phenolic foam with unsatisfactory thermal insulation properties.

In contrast, the aqueous phenolic resoles of this invention do not have the above-mentioned disadvantages. When these resoles are formulated into foamable mixtures and cured using as much acid as is needed to foam and cure the mixture in a reasonable commercial time, they do not generate heat too quickly or too much. The preferred foamable phenolic resole mixtures of this invention generally reach maximum pressure about 2-3 minutes after the addition of the acid catalyst. During this period, the mixtures reach a temperature of about 74-79 ° C. During this period, the temperature should never exceed 93 ° C and preferably never 88 ° C. When preferred resoles and foamable resole mixtures are used, the pressures formed are usually 0.28 to 0.42 kp / cm above atmospheric pressure. Thus, phenolic foams can be prepared which have captured substantially all of the blowing agent and have cell walls that have not ruptured. In addition, the viscosity of the resole blends to be foamed is high enough to trap the blowing agent during the initial stages, and the phenolic resoles do not significantly flow, resulting in stronger and thicker cell walls.

The aqueous phenol resole of this invention is a substantially phenol-formaldehyde condensation polymer having a molar ratio of formaldehyde to phenol of about 1.7: 1 to about 2.3: 1, preferably about 1.73: 1 to about 2.25: 1, and most preferably about 2: 1. The phenolic resole has an average (weight) molecular weight of at least about 800 and most preferably about 950 to 1500. The phenolic resole also has an average (number) molecular weight of at least about 350, preferably about 400 to 600, and a dispersibility of more than 1.7, most preferably about 1.8 to 2 , 6. The phenolic resole of this invention may be a mixture of more than one resole if the resulting resole mixture meets the required properties.

The aqueous phenol-formaldehyde resoles of this invention are prepared by reacting the desired molar ratios of phenol and formaldehyde in the presence of a basic catalyst until the resulting phenolic resole has the desired molecular weight and dispersibility. The reaction can be performed using any methods previously known in the art. For example, phenol, formaldehyde, and catalyst can be charged to the reactor in the desired molar amounts and reacted until the desired molecular weights are achieved. Alternatively, one or two ingredients may be placed in the reactor and the remaining ingredients added to the reaction mixture over time. In the preferred method of preparing the aqueous phenolic resole, phenol is added to the reactor and the basic catalyst and formaldehyde are metered highly or continuously during the initial stage of the condensation reaction. The method of preparation of the phenolic resin is not critical if the phenol and formaldehyde condense in the desired molar ratio and the products have the desired properties in terms of molecular weight and dispersibility.

It was mentioned above that in a phenolic resole, the molar ratio of formaldehyde to phenol should be about 1.7: 1 to 2.3: 1. If the ratio is greater than 2.3: 1, then the resulting phenolic foam may contain residual free formaldehyde and cause an odor problem. In addition, under mo conditions above 2.3: 1, phenolic resales are obtained in which the heat generation is too slow and the processing viscosity is too high. Phenolic foams made from resoles with a molar ratio of more than 2.3: 1 also tend to be too brittle and have poor compressive strength. If the molar ratio is less than 1.7: 1, then the resol has too low a viscosity, resulting in thin cell walls. Phenolic resoles with a molar ratio of less than 1.7: 1 are also highly exothermic, making it difficult to capture the effluent and prevent cell wall rupture. Phenolic foams made from these resoles also shrink too much.

The average (weight) molecular weight of the phenolic resole should be greater than about 800, preferably between 930 and 1300.

If the average (weight) molecular weight is less than about 800, the phenolic resin is too reactive and not sufficiently viscous. In phenolic resoles with average (weight) molecular weights of less than 800, the pressures of heat generation peaks are too fast and high.

These resoles also reach an exothermic temperature above 93 ° C during this period. This rapid and intense heat generation causes many cell walls to rupture and the fluorocarbon blowing agent to disappear before the cells have formed. In addition, phenolic resins having average (weight) molecular weights of less than 800 give foamable phenolic resole mixtures having too low a viscosity to form strong, thick cell walls. These phenolic resins tend to drain in the early stages of foaming and curing to form thin-walled cell walls. The blowing agent easily punctures thin cell walls and they crack easily during drying and use.

The upper limit of the average (weight) molecular weight is determined for practical reasons. Resoles with molecular weights above 1,500 are often very viscous and quite difficult to handle. However, they can be made into acceptable 16,73445 foams.

The phenolic resoles have an average (number) molecular weight of greater than about 350, preferably about 400 to 600, and a dispersibility of more than about 1.7, most preferably between 1.0 and 2.6. If the average (number) molecular weight is less than 350 or the dispersibility is less than about 1.7, then the phenolic resole has too low a viscosity. In addition, the phenolic resole is too reactive, i. its heat generation is too large and too fast. The blowing agent is difficult to capture and the rupture of cell walls is difficult to prevent.

Phenolic foams made from these resoles also have a shrinkage problem and have thin cell walls.

If the average (number) molecular weight is greater than about 600 or the dispersibility is greater than 2.6, the resoles are often too viscous to handle and react too slowly. These ceilings are determined for practical reasons. Resoles with average (number) molecular weights and dispersibility above these limits can be made into acceptable foams.

The phenolic resoles of this invention may have a free formaldehyde content of up to about 7% by weight of resole and a free phenol content of up to about 7% by weight. The free formaldehyde and phenol are preferably less than about 4% by weight. Too much formaldehyde can cause an odor problem. In addition, free formaldehyde and phenol affect the reactivity and viscosity of the phenolic resole and the foamable mixture.

The phenolic resoles of the present invention generally have a viscosity of about 1,000 centipoise to about 20,000 centipoise in 16% water and 25 ° C. The viscosity is best between about 6,000 and 10,000 centipoise. Viscosity is not critical as long as the molar ratios, molecular weights and dispersibility are as set forth above. It is possible to prepare phenolic resoles, 17 73445 having the above viscosities but not the required molecular weights and dispersibility. Such resoles are not included in the present invention. Resoles. , whose viscosities are in the above range, especially in the recommended range, are desirable because they can be easily formulated into a uniform foamable phenolic resolution with conventional equipment see i.

in addition to the use of phenol, up to about 10% of phenol can be replaced by other phenolic compounds. Examples of other suitable phenolic compounds are · resorcinol; katekoii; ortho-, meta- and para-k re so 1it; xylenols; ethylphenols: p-tert-butylphenol and the like * -. Phenolic phenolic compounds can also be used. The preferred phenolic resoles contain mainly the phenol itself and only minor amounts, if any, of other phenolic compounds.

In addition to the use of formaldehyde, up to about 10% of formaldehyde can be replaced by other aldehydes. Examples of other suitable aldehydes are qyoxal, α dehyde, chloral, furfural and benzaldehyde. The preferred phenolic resoles contain mainly formaldehyde itself and only minor amounts, if any, of other aldehydes. as used herein, the term phenolic resol i encompasses resoles containing minor amounts of phenolic compounds other than phenol and / or minor amounts of aldehydes other than formaldehyde.

The phenol component is added to the reactor as an aqueous solution. The concentration of phenol can be between about 50% and about 95% by weight, solutions containing less than 50% by weight can be used, but the reaction mixture obtained is very dilute and thus has a longer reaction time to obtain the desired resolution. It is possible for myrrh to use pure phenol; however, the use of pure phenol does not provide any advantage over aqueous phenolic solutions with concentrations of more than about 85% by weight. The preferred method uses concentrated phenol solutions with a concentration of 88% by weight or more.

The formaldehyde component is added to the condensation reaction at basket concentrations of about 30 to about 97 weight percent. Solutions containing less than about 30% by weight of formaldehyde can be used, but the resulting reaction mixture is very dilute and thus a longer reaction time is required to achieve the desired molecular weight. The preferred method uses concentrated sources of formaldehyde at a concentration greater than 85% by weight. The preferred method uses paraformaldehyde as the source of formaldehyde.

the condensation of phenol and formaldehyde is catalyzed by a base. Commonly used basic catalysts are alkali and alkaline earth metal carbons, carbonates, bicarbonates or oxides; however, other basic compounds may be used. Examples of useful catalysts include lithium hydroxide, sodium hydroxide, lum hydroxide, barium hydroxide, lithium oxide, potassium carbonate and the like. Commonly used catalysts are. sodium hydroxide, barium hydroxide and also lium hydroxide i. The preferred method uses potassium hydroxide.

Although the molar ratios of phenol and formaldehyde are critical, other parameters of the condensation reaction, such as time, temperature, pressure, catalyst concentrations. The concentration of the reactants and the like are not critical.

These parameters can be adjusted as follows. to obtain a phenolic resole having the desired molecular weight and dispersibility. It is noteworthy that in the preferred process, the concentrations of phenol, formaldehyde and catalyst are very important.

the reaction of phenol and formaldehyde is usually carried out at temperatures between about 50 and 150 ° C. The preferred reaction temperature range of 19,73445 is from about 70 to about 95 ° C. It is noteworthy that the reaction time depends on the temperature.

The reaction pressure can vary widely from atmospheric pressure to about 6 atmospheric pressure. The reaction can also be carried out under reduced pressure.

The catalyst concentration can range from about 0.005 to about 0.10 moles of base per mole of phenol. The range is preferably from about 0.005 to about 0.03. In the most preferred process, the catalyst concentration is from about 0.010 to about 0.020 moles of base per mole of phenol.

The time of the condensation reaction depends on the temperature used, the concentrations of the reaction components and the amount of catalyst. The reaction time is usually at least 6 hours but not more than 20 hours. It is noteworthy that the reaction lasts until the phenolic resol has the desired molecular weight and dispersibility.

The completion time of the reaction can be confirmed by determining the molecular weights and dispersibility as described above; however, this is time consuming and it takes time to obtain the results of the assays. According to the invention, it has been found that there is a strong correlation between bubble viscosity and molecular weights and dispersibility at certain molar ratios and operating parameters. For example, in a preferred commercial process for preparing a 2: 1 molar resole using concentrated phenol, concentrated formaldehyde, and large amounts of cata 1, it has been found that a bubble viscosity of 60 seconds correlates with molecular weights and dispersibilitys in the preferred ranges. Thus, it is possible to use bubble viscosity as an indication of achieving the desired molecular weights and dispersibility; however, the actual molecular weights and dispersibility are still predominant. In addition, if changes are made to the molar ratios or process operating parameters, the correlation of the bubble viscosity to the molecular weights and dispersibility must be determined under these conditions.

Since the condensation reaction is base catalyzed, the phenolic resole obtained is alkaline. It is desirable to adjust the pH of the phenolic resole to between about 4.5 and 7.0, most preferably 5.0 to 5.0, to prevent condensation reactions from continuing.

The pH is adjusted by adding an acid or acid-forming compound. Examples of useful acids are hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, oxalic acid and antacid. The preferred acid is formic acid.

Renol formaldehyde resole is obtained as an aqueous solution containing from about 25% to about 95% by weight of resole. The final k o n concentration depends on how much water has been introduced with the reaction components and catalysts, which are generally used as aqueous solutions. In addition, water is formed as a by-product of the condensation reaction. In the preferred process, the concentration of phenolic resole obtained is generally about Θ0 to 90% by weight. The phenolic resole can be easily adjusted to the desired water content by stripping in the normal manner at reduced pressures and low temperatures. In preparing the phenol-formaldehyde reso of this invention, the phenol and formaldehyde are reacted in the presence of a basic catalyst until the resole has the desired molecular weight and dispersibility. The pH of the aqueous resole is then adjusted and the aqueous resole is cooled to about 20 ° C. If the molecular weight of the pH-adjusted aqueous resole is too low, it can be further strengthened until the desired molecular weight is reached. The amplification of pH-adjusted resoles to increase molecular weight is known in the art. However, since such amplification is slow compared to the base-catalyzed reaction, it is desirable to react and amplify the phenol and formaldehyde immediately to the desired molecular weight before adjusting the pH and cooling.

The aqueous phenol forms of the present invention 21 -. ., 73445 aldehyde resoles are particularly useful in the preparation of phenolic foam having a low k value as well as other excellent physical properties required for phenolic foam insulators. The aqueous phenolic resoles of this invention can also be easily processed into phenolic foam. Phenolic resoles can be processed into phenolic foam in a uniform and reproducible manner.

The phenol-formaldehyde resoles of this invention are used to make phenolic foam. First, the aqueous phenolic resoles are formulated as a foamable phenolic resole mixture. The foamable phenolic reso mixture contains the phenolic resole of this invention, a blowing agent, especially a hydrocarbon, a surfactant, an acid catalyst, and optional additives such as plasticizers, formaldehyde scavengers, and the like.

In the method of making the phenolic foam, the foamable phenolic resin mixture to be foamed is usually introduced into a substantially closed mold and the mixture is allowed to foam and cure in this mold. The mold withstands the pressures created by the foam mixtures. The amount of pressure depends on such factors as the amount and type of blowing agent, the amount and type of acid catalyst, and the amount and type of resole. When using the resoles of the invention, the pressure developed is generally about 0.21 to 1.05 kp / cm above atmospheric pressure, and the mold should be designed accordingly. Preferred phenols, when formulated as preferred foamable mixtures, form about 0.28-2 0.42 kp / cm pressure above the atmosphere. The mold should withstand pressures approximately equal to those developed by the foam composition to prevent cell wall rupture. The foamable phenolic resole mixture contains a special phenolic resole of this invention. The amount of the phenolic reso mixture to be foamed applied to the mold depends on the desired density of the phenolic foam, etc. The various components of the phenolic reso mixture to be foamed can be mixed together in any order, provided that the resulting mixture is uniform.

22 73445

However, it should be noted that the preferred anhydrous phosphoric acid causes the mixture to be foamed to foam within a few seconds after mixing with the phenolic resole and the foam mixture reaches maximum pressure within a few minutes. The catalyst should thus be the last component added to the foamable phenolic resolution mixture. In the preferred continuous method, some of the components may be premixed before being added to the mixed it usage. However, for the reasons set out above, the catalyst should be the last ingredient to enter the mixer.

In an embodiment of the invention commonly used in the laboratory, the foamable phenolic resolution mixture is introduced into a rigid, closed mold, as shown, for example, in Figures 1A and 1B. The foamable phenolic resolution mixture initially expands substantially at atmospheric pressure. As the foamable mixture expands to fill the mold, it exerts pressure against the walls of the mold. The mold is made to withstand pressures of about 1.05 kp / cm above atmospheric pressure.

Reference is now made to Figures 1A and 1B. The mold consists of a top plate 1, a bottom plate 2, side walls 3 and end walls A. The hinges 5 hold the side walls 3 and the other end wall A together. In a closed position, the bolts 6 and threaded nuts 7 hold the top and bottom plates and side walls in place. In addition, a number of C-clamps 8 are attached around the circumference of the mold during the flotation and curing steps to withstand possible pressures. The mold is also provided with a pressure transducer 9 which measures the mold pressure and a thermocouple 10 for measuring the mold temperature. The operation of the laboratory mold is described in more detail below. The size of the mold can be changed by resizing the walls and plates.

In another embodiment, in the preferred continuous processing technique, the phenolic foam is introduced into a two-belt press-type device, generally 2> 73445 illustrated in Figures 2-5. The ingredients of the foamable phenolic resole mixture containing the resole of this invention are dispensed in the desired ratio into a suitable mixing device (not shown) and then applied to a lower coating material 25, such as paperboard containing a thin layer of aluminum, glass mat, rigid substrate such as hardboard or vinyl. This material comes from a container (not shown) and moves along the table 29 taken by a lower conveyor 12. The foamable resolution mixture is applied by means of a suitable dispensing device 30 which reciprocates transversely to the direction of movement of the lower coating material 25, although any other suitable device may be used to distribute the mixture evenly, such as a multi-flow mixer head or nozzle set. with the upper cover material 27 guided by the rollers 22 and 23 at a point where the mixture to be foamed is at a very early expansion stage. As the mixture to be foamed initially expands substantially at ambient atmospheric pressure, it is introduced into a curing space 28 formed by the lower part of the upper conveyor 11, the upper part of the lower conveyor 12 and two fixed, rigid side walls called side rails. These are not shown in Figure 2, but in Figure 3 they are indicated by reference numerals A1 and A2. The distance of the upper conveyor 11 from the lower conveyor 12 determines the thickness of the foam. The upper conveyor 11 can be moved by any suitable lifting device (not shown) perpendicular to the lower conveyor 12, which instead cannot be raised or lowered. When the upper conveyor 11 is raised or lowered, it moves as shown in Fig. 3 between the fixed rigid side walls A1 and A2, which walls are immediately adjacent to the sides of the upper conveyor 11. The surfaces of the conveyor which come into contact with the upper and lower cover material consist of a plurality of pressure plates 13 and IA, which are fastened to the conveyor by means of a rigid fastening device 21. If necessary, the pressure plates 73445 2α can be heated by means of hot air which is led to the upper and lower conveyors and circulated inside them by means of air ducts not shown in the drawing.

Simultaneously with the upper and lower cover papers, foam-releasing side papers 43 and 44, shown in Fig. 3, are introduced into the curing space, such as a thin polyethylene film by means of rollers 45 and 46 and guides 47 and 50. Each guide is positioned just in front of the curing space 28 so that the side papers 43 and 44, before coming into contact with the side walls 41 and 42, go over the upper and lower end material 1, for example as shown in Figure 4. Upon contact with the side walls 41 and 42, the side papers 43 and 44 are straightened, as illustrated in Figure 5.

When the foam has expanded to fill the curing space, the expansion plates are limited by .13 and 14, Fig. 2, and the sidewalls 41 and 42, Fig. 3. The pressure exerted by the foam on the pressure plates and sidewalls varies as described above, but is typically between about 0, 21 - 1.05 kp / cm above atmospheric pressure. The pressure plates 13 and 14 and the side walls 41 and 42 are made to withstand these pressures.

Process parameters such as the amounts of components of the phenolic resole mixture to be foamed, the flow rate of the mixture from the dispenser and the speed of the conveyor can be varied widely to provide a phenolic foam of the desired thickness, density, etc. The foamable mixture should be used fills the curing space and applies pressure against the walls of the space.

After the phenolic foam has cured. the side papers 43 and 44 are removed from the dirt, for example by means of the rollers 43 and 49 shown in Fig. 3. The foam can be cut as desired

II

25 7 3 4 4 5 depending on the intended use.

The amount of aqueous phenolic resole in the foamable phenolic resole mixtures used to make substantially closed cell phenolic foams can vary within wide limits, provided that it is so large that a foam having the desired density and compressive strength is obtained. The phenolic resol is generally present in the foamable mixture in an amount of about 40 to 70% by weight of the mixture. It is best present in the foamable mixture in an amount of about 45 to 55% by weight. These weight percentages of phenolic resole in the foamable mixture are calculated as 100% active phenolic resole. Since the resole is in aqueous solution, the actual concentration of resole must be taken into account when calculating the amount of aqueous resole solution consumed in the phenolic resolution to be foamed.

Any suitable blowing agent can be used. When choosing a blowing agent, it must be remembered that the k-value of the phenolic foam is directly related to the k-value of the blowing agent remaining in the phenolic foam. Although blowing agents such as n-pentane, methylene chloride, chloroform and carbon dioxide can be used, they are not recommended because they do not have the excellent thermal insulation properties of fluorocarbon blowing agents. In addition, fluorocarbon blowing agents do not dissolve in phenolic foam and thus do not diffuse out over time, while some of the above-mentioned blowing agents have a certain compatibility with phenolic foam and can thus diffuse out over time. However, they can be used in combination with the preferred fluorocarbon blowing agents. It is recommended that the blowing agent contains a chlorofluorocarbon blowing agent. Examples of suitable fluoro-hydrocarbon blowing agents are: dichlorodifluoromethane: 1,2-dichloro-1,2,2,2-tetrafluoroethane; 1,1,1-trichloro-2,2,2-trifluoroethane; trichloromonofluoromethane and 1,1,2-trichloro-1,2,2-trifluoroethane. The blowing agent may be a single blowing agent compound or it may be a mixture of such 26 7 3 4 4 5 compounds. The boiling points of commonly used fluorocarbon blowing agents at atmospheric pressure, i.

760 .mmHg in absolute pressure, are between about -5 and about 55 ° C. A typical boiling point at atmospheric pressure is between about 20 and about 50 ° C. The preferred blowing agent is a mixture of trichloromofluoromethane and 1,1,2-trichloro-1,2,2-trifluoroethane. It is particularly preferred that the weight ratio of trichloromonofluoromethane to 1,1,2-trichloro-1,2,2-trifluoroethane in the mixture is 1: 1 to 1: 3.

The blowing agent is generally present in the foamable mixture in an amount that forms a substantially closed cell phenolic foam with a low initial k-value. The amount of blowing agent can vary widely, but is usually between about 5-20% by weight of the mixture to be foamed.

A typical amount of blowing agent is about 5-15% by weight of the mixture to be foamed. The preferred amount is between about 8-12% by weight.

The foamable phenolic resole mixture also contains a surfactant. The surfactant should have properties that cause it to effectively emulsify the aqueous phenolic resole, blowing agent, catalyst, and optional additives in the foamable mixture. To produce a good foam, the surfactant should lower the surface tension and stabilize the foam cells during foaming and curing. Non-ionic, hydrolyzed mats have been found to be most useful. hornat silicone glycol surfactants, although any surfactant having the above properties may be used. Specific examples of suitable silicone surfactants include Union Carbide Corporation's silicone surfactants 1-7003, L-5350, L-5420 and L-5340 (the latter being preferred) and General Electric Company's iconic surfactant. -active substance SF-1188. Another useful class of surfactants are nonionic organic surfactants, such as condensation products of alkylene oxides such as ethylene oxide, propylene oxide, and mixtures thereof with alkylenes such as nonylphenol, dodecylphenol, and the like. Other suitable organic surfactants are also known, such as those disclosed in U.S. Patent 2,289,094, which is incorporated herein by reference for organic surfactants.

Another class of suitable surfactants that may be applicable to this invention are siloxane-oxyalkylene copolymers, such as those containing Si-O-C and Si-C bonds. Typical siloxane-oxyalkylene copolymers contain a siloxane moiety, either consisting of repeating dimethylsiloxy units terminated at the terminal position with monomethylsiloxy and / or trimethylsiloxy units, and an organic group having at least one polyoxyalkylene chain consisting of oxyethylene and an ethylene chain at the end. Individual examples of suitable siloxane-oxyalkylene polymers can be found in U.S. Patent 3,271,331, which is incorporated herein by reference for siloxane-oxyalkylene surfactants. The surfactant must be carefully selected, as some of these adversely affect the viscosity of the phenolic resole mixture to be foamed or collapse the foam before the take-up cures.

The surfactant used in the foamable composition may be a single surfactant or a mixture of these agents. In the present invention, the surfactant is used in such an amount that it is sufficient to form a good emulsion. The amount of surfactant is generally about 0.1 to 10% by weight of the weight of the phenolic resole mixture to be foamed. A typical amount of surfactant is from about 1% to about 6% by weight of the mixture. The preferred amount of surfactant is from about 2% to about 4% by weight of the mixture.

28 7 34 4 5

The surfactant may be mixed separately with the phenolic resole, blowing agent and catalyst to form a foamable phenolic resole, or it may be mixed with the phenolic resole or blowing agent before being mixed with the other components. Alternatively, a portion of the surfactant may be premixed with the phenolic resole and a portion may be premixed with the blowing agent. It is recommended that about 1/3 of the surfactant be premixed with the fluorocarbon blowing agent and 2/3 premixed with the phenolic resole.

Although water is believed to be the main cause of cell wall openings and to contribute to cell wall rupture, the presence of water is essential. First, it is very difficult and expensive to make a resole from phenol that contains little or no water. In addition, the anhydrous phenolic rosols having the properties of the resoles according to the invention are extremely difficult to handle. They are highly viscous and difficult to formulate into foamable mixtures.

In addition, the exotherm of the reaction is difficult to control without water. The foamable phonolic resolution thus requires water to adjust the viscosity of the phenolic resole and the resulting foamable phenolic resolution to be favorable for the production of phenolic foams. In addition, water acts as a necessary heat well and helps to control the exothermic flotation and curing reaction. Most of the water is in the aqueous phenolic resole, although limited amounts of water can be transferred in the fluorocarbon blowing agent or surfactant. The amount of water in the foamable phenolic resolution is usually 5 to about 20% by weight of the mixture to be foamed. The preferred amount is about 7-16% by weight. In addition, it is important that in the aqueous resol, the water is evenly mixed with the resole. If the aqueous resole contains water that is not evenly mixed with the resole, ruptured cell debris may result.

29 7 3 4 4 5

The hnppokata lyy11i component of the foamable phenolic rosis can be any strong organic or inorganic acid, i.e., the pKa is less than about 2.0. Examples of strong organic acids are hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid. Examples of strong organic acids are trichloroacetic acid, picric acid, benzenesulfonic acid, toluenesulfonic acid, xylenesulfonic acid, phenisulfonic acid, methanesulfonic acid, ethanesulfonic acid, butanesulfonic acid and the like. Mixtures of one or more of the above acids are also possible.

It has been mentioned above that one of the disadvantages of the prior art phenolic foam is the small openings in the cell wall. Water, especially water in the catalyst, is believed to be the main cause of cell wall openings and is also believed to increase the bursting of cell walls. The acids should therefore contain as little water as possible. Preferred catalysts are certain anhydrous arylulfonic acids, which are the subject of a co-pending patent application. Of the anhydrous aryl sulfonic acids, toluecisulfonic acid and xylenesulfonic acid are preferred, and a mixture of the two is preferred.

The amount of acid curing catalyst in the foamable phonolic reso mixture can vary over a relatively wide range.

The practical limitation is that the amount of katnlyyH used is about .10 seconds - 1 mine! in rise time and 0.5 to 5 minutes ko vo f. t: nm i sa i ka. The amount of anhydrous catalyst is generally about 6 to 20% by weight of the mixture to be foamed, preferably about 12 to 16% by weight. In addition to the aqueous phenolic resole, the fluorocarbon blowing agent, the acid catalyst, and the surfactant, the foamable phenolic resole mixtures may contain other substances known in the art in amounts used for normal use. Examples of optional optional ingredients are given below. Resorcinol or urea, usually 0.5 to 5% by weight, may be added to remove the free form aldehyde. Plasticizers such as triphenyl phosphate, dimethyl terephthalate or dimethyl isophthalate may be added in substantially amounts of about 0.5 to 5% by weight. The anti-glow agent, the anti-cracking agent and the anti-pollution agent may be added in amounts usually in the range of about 0.5 to 5% by weight. Preferred foamable phenolic resole mixtures contain about 3% by weight of urea and about? weight percent of plasticizer. Urea and plasticizer are best mixed with the phenolic resole before it is mixed with the other ingredients of the foamable phenolic resole mixture.

Aqueous phenolic resoles are useful as foundry binders, wood adhesives, plywood and particle board binders, and low shrinkage mold compounds; however, aqueous phenolic resoles are most useful in the manufacture of phenolic foam thermal insulation for a wide variety of household and industrial applications.

The invention is particularly advantageous as a process for the preparation of phenolic foams with excellent properties from foamable mixtures based on phenolic resoles made from relatively inexpensive phenol and preferably from formaldehyde in the form of paraformaldehyde. Phenolic foam prepared using the resoles of the invention has not only a good initial k-value but also a well-preserved k-value, in contrast to phenolic foams generally known in the art. The resoles according to the invention have thus achieved a long-term goal, which has not been achieved so far. They have been used to prepare phenolic foam with both a good initial k value and a well-preserved k value from phenolic resoles such as simple phenol formaldehyde resoles. They are therefore an important step forward in this area.

31 73445

The various properties of phenol formaldehyde resoles and phenolic foams prepared therefrom were determined by the following methods, unless otherwise stated.

The viscosity reported as bubble viscosity was determined at 25 ° C in a Gardner-Holdt bubble viscosity tube by ASTM method D-1545-76. Viscosity is expressed in seconds, bubble seconds, or bubble viscosity.

The viscosity, expressed in centipoise (cp), was determined by Bro ok Filed viscosity, model RVF. Measurements were made with a resolution of 25 ° C and the probe was selected so that the mid-range reading was obtained at 20 rpm. Probe No. 5, ASTM D-2196 was used for most readings)

The pH of the resin was measured with a pH meter (Fisher Accumet pH Meter Model 610 A). The pH electrode was standardized to pH 4.0, 7.0, and 10.0 before each use. (ASTM E-70).

The phenol content in the resole was measured with an IR spectrophotometer. The IR assay was performed using a recording IR spectrophotometer with sodium chloride optics (Perkin Elmer Model No. 21), sealed liquid absorption cells, and 0.1 mm sodium chloride windows. The method measured the IR abeorbance (14.40 microns) of the acetone solution of phenolic resole.

The phenol content of the resole sample was then determined by comparing the absorbance of the sample with the absorbance of standard solutions of known phenol content measured under identical conditions. The repeatability of this method has been found to be + 0.14%.

The amount of free formaldehyde in the phenolic resol was determined by the hydroxylamine hydrochloride method. In the method, a resole sample is dissolved in methanol, the pH is adjusted to the bromophenol blue endpoint, and an excess of hydroxylamine hydrochloride is added. The reaction liberates hydrochloric acid, 32 7 3 4 4 5 which is titrated with standardized sodium hydroxide to the same end point of bromophenol blue,

First, weigh a resole sample to the nearest 0,1 mg (usually 1 to 3 g of sample) into a 150 cm 2 beaker containing 10 cm 2 of methanol. The mixture is stirred until the resole is completely dissolved. The amount of resole sample should be such that more than 1/3 of the amount of hydroxylamine hydrochloride remains after the reaction is complete. After dissolving the resole in methanol, 10 cm <3> of distilled water and 10 drops of bromophenyl-blue indicator are added. The pH of the sample solution is adjusted by the dropwise addition of 0,5 N sodium hydroxide or 0,5 N sulfuric acid until the indicator just turns blue.

Then 25 cm -1 of hydroxylamine hydrochloride solution (ACS grade) is pipetted into the beaker and the reaction is allowed to proceed at room temperature for 15 minutes. The solution is then rapidly titrated with 0.5 N sodium hydroxide solution to a blue color to which the sample solution has previously been adjusted. The sample solution is stirred with a magnet during the titration. The intensity of the mixing should be high when approaching the end point. At the same time, a similar procedure is followed for the blank using all other ingredients except for the sample. The free formaldehyde content of the sample is then calculated as follows: (V -V) x N x 3,001

Free formaldehyde (%) = _ ·

W

where V. = volume in cm of 0,5 N sodium hydroxide solution used to titrate the sample.

V- = 0,5 N used for the titration of the blank

* 3 volume of sodium hydroxide solution in cm.

N = normality of the sodium hydroxide solution W = weight of the resole sample in g.

3.001 = A constant that converts the gram-equivalent weight of formaldehyde to a percentage.

33 73445 Further information on this method is given in G.M.

In Kline's book "Analytical Chemistry of Polymers", High Polymers, Vol. Part II 1, Interscience Publishers, Inc.

(1959).

The water content of the resoles was measured by the method of Karl Fischer, which had been modified so that the end point of the titration was determined electrically. The device used was an Automatic Karl Fischer Titrator, Aquatest II (Photovolt Corp.) and the device was assembled, filled and electrically connected according to the manufacturer's instructions. Weigh into a clean, dry volumetric flask the amount of resole sample suggested in the following table. Add 20 to 50 cm 2 of pyridine or methanol to the flask, close the flask and mix the solution well until the resole sample is completely dissolved. The solution is diluted to volume with dry pyridine or methanol, the flask is closed with a cap-type rubber stopper and the solution is mixed by shaking the flask.

Estimated sample size

Resole weight (g) Final final estimated amount of sample _________________ volume (cm j_ (weight? 0) _ 3-4 50 0.3-5 2-3 100 5-15 1-2 100 15-25 1 100> 25

Using a suitable dry syringe and needle, draw a 1 or 2 cm 2 test sample into the syringe and empty the syringe into a waste container. This rinse is repeated several times. The sample is then drawn into the syringe until the volume is slightly above the desired calibration mark and then adjusted to the desired mark. Wipe the syringe needle clean with tissue paper and insert the needle through the septum of the sample port until it is below the surface of the titration solution. The sample is then injected into the titration solution and the syringe is quickly removed. Automatic titration is started and the results are saved when the titration is complete. The water content of the blank is also determined as described above 34 734 4 5.

The percentage by weight of water is calculated as follows: «vv

Water content (by weight? 0) r_ * 1 'W x 10.000 where = reading indicating the total amount of water in pg in the analyzed sample = reading indicating the total amount of water in pm in the blank sample V2 = volume in cubic centimeters, to which the dissolved sample was diluted V = the volume of the titrated sample expressed as cm 2 R = reso1 sample weight.

Further information on this method is reported in: Mitchell, J. Sr., and Smith, D.M., "Aqametry", Chemical Analysis Series, Vol. 5, Interscience Publishers Inc. (194Θ).

The average (weight) molecular weight, average (number) molecular weight and dispersibility of the resoles were determined by gel permeation chromatography. The apparatus used was a Gel Permeation Chromatograph from Waters Associates, Inc. with five columns arranged in series and packed with Styragel gel (1 column each).

The pore sizes of Sty rage1-gee1 were as follows: 1 in column 1000A, 2 in column 500A, and 2 in column 100A. Detection was performed using a differential refractive index (Waters Differential Refractometer R401). Tetrahydrofuran (THF) was used as the solvent in the system and the flow rate was 2 ml / minute. A resole sample weighing about 220-250 mg was dissolved in 25 ml of tetrahydrofuran. To avoid variations due to solvent evaporation, the solutions were treated with minimal exposure to air and weighed in sealed bottles.

35 7 3 4 4 5 The GP chromatograph was calibrated using monodispersed polystyrene as a standard polymer against which the resole was measured. Calibration was performed at room temperature using tetrahydrofuran as the polystyrene solvent.

The results of the GP chromatography were recorded and processed on a Waters Associates data processor (730 Data Module) which performed all calculations and printed the finished analysis results. Detailed information on the measures is provided in the Waters literature. See also Waters Publication No. 82475, entitled "GPC, Data Reduction & the 730-150 C Combination" and Waters Technical Brief No. 102, "HLPC Column Perfomance Rating", k-values were measured by ASTM method C-518 (Revised) on uncoated inner samples.

The following examples illustrate the invention. Parts and percentages are by weight unless otherwise indicated.

Example 1 A phenol-formaldehyde resole according to the present invention with a molar ratio of formaldehyde to phenol of 2: 1 was prepared in a laboratory in a 4-liter reactor equipped with a reflux condenser, a thermocouple indicating DC temperatures, an addition funnel, a two-bladed propeller air mixer and reactor heating ). First, 1434 g of 90% phenol (13.73 moles) was weighed and added to the reactor. 1207 g of flake paraformaldehyde (91%, 36.61 moles) were then weighed and added to the reactor.

This mixture of phenol and formaldehyde was stirred at 78 ° C during heating. In the meantime, a 45% aqueous solution of potassium hydroxide was prepared. Then, 35.53 g of a 45% potassium hydroxide solution (0.285 mol) was added to 478.4 g of 90% phenol (4.58 mol) and mixed well. This mixture of potassium hydroxide and phenol was then placed in an addition funnel. After the reactor temperature 3β 73445 had risen to 78 ° C, this solution of potassium hydroxide and phenol was added dropwise over 150 minutes. During the addition, the reactor temperature was maintained between 78 and 80 ° C by heating and / or cooling the reactor. In the early stages of the addition, the reactor had to be cooled from time to time to control the exothermic reaction. There was also a slight gel development during the initial stages, but the gel disappeared during the addition period. During the gel, the temperature was carefully monitored because the heat transfer through the gel is slow.

After the mixture of phenol and potassium hydroxide was completely added, the reaction mixture was heated to 85-88 ° C and maintained at this temperature. At 25 ° C, bubble viscosities were determined from Grdner and Holdt bubble viscosity tubes k e 11a (ASTM D-1545-76) samples of the reaction mixture taken every 30 minutes after the temperature had risen to 85-88 ° C. When the bubble viscosity was obtained for about 15 seconds, the reaction mixture was gradually cooled (about 15 minutes) to about 68-79 ° C. When this temperature was consistently reached, bubble viscosities were determined again every 30 minutes until a bubble viscosity of about 30 seconds was obtained. Thereafter, bubble viscosities were determined every 15 minutes until a bubble viscosity of about 60 seconds was obtained. After a viscosity of 60 seconds, 14.57 g of a 90% formic acid solution (0.285 mol) was added to the reactor, and the reaction mixture was cooled to 55 ° C. After the reaction temperature dropped to 55 ° C, 190 g of Morflex 1129 plasticizer (dimethyl isophthalate) was added and allowed to dissolve. The reaction mixture was then transferred to a container and refrigerated until use. The resulting resole had a Brookfield viscosity of 6600 centipoise at 25 ° C. The resole contained 1.9% free phenol, 3.6% free formaldehyde and 17.3% water. The average (weight) molecular weight was 981, the average (number) molecular weight was 507 and the dispersion was 1.93.

37 73445

Example 2 A phenol-formaldehyde resole of this invention having a molar ratio of formaldehyde to phenol of 2: 1 was prepared on a commercial scale in a 3800 liter reactor equipped with a reflux condenser, a Celsius thermocouple, precision chemical addition equipment, mixture stirrers and reaction mixture heating.

First, 1726.20 kg of 90% phenol (16,542.3 grams) was charged to the reactor. 1452.92 kg of flakes of para formaldehyde (91%, 44,111.78 grams) were then added to the reactor with stirring. This mixture of phenol and formaldehyde was stirred with heating to 78 ° C and maintained at this temperature for about 2 hours. Meanwhile, a solution of potassium hydroxide and phenol in a mixing tank was prepared by mixing well 575.40 kg of 90% phenol (5,514.14 grams) and 42.84 kg of a 45% KOH solution (343.92 grams).

After 2 hours and when the initial reactor temperature was 78 ° C, a solution of potassium hydroxide and phenol was added to the reactor at a rate of 3.41 to 5.11 liters per minute over 2-1 / 2 hours. During the addition period, the reactor temperature was maintained between 78 and 82 ° C by heating and / or cooling the reactor or temporarily stopping the addition of phenol-potassium hydroxide.

After the entire mixture of phenol and potassium hydroxide was added, the reaction mixture was heated to 85-88 ° C and maintained at this temperature. Bubble viscosities were determined at 25 ° C in a Garder and Holdt bubble viscosity tube (ASTM D-1546-76) from samples of the reaction mixture taken every 30 minutes after the temperature had risen to between 85 and 88 ° C. When the bubble viscosity was obtained at about 38,73445 for 15 seconds, the reaction mixture was gradually cooled to about 68-79 ° C. When this temperature was reached, bubble viscosities were determined again every 15 minutes until the viscosity was about 30 seconds. Thereafter, bubble viscosities were determined every 15 minutes until a bubble viscosity of about 60 seconds was obtained. With a bubble viscosity of 60 seconds, 17.56 kg of a 90% formic acid solution (343.90 grams) was added to the reactor and the reaction mixture was cooled to 55 ° C. When the reaction mixture was 55 ° C, 107 kg of Morflex 1129 plasticizer was added and allowed to dissolve.

The reaction mixture was then transferred to a storage tank and kept refrigerated until use. The resulting resole had a Brookfield viscosity of 7.7400 at 25 ° C. The resole contained 3.2% free phenol, 3.5% free formaldehyde and 14.6% water. Resol had an average (weight) molecular weight of 1222, an average (number) molecular weight of 550 and a degree of dispersion of 2.22.

Example 3

A phenol-formaldehyde resole with a molar ratio of formaldehyde to phenol of 2: 1 was prepared in the laboratory using the preferred method. The reaction was carried out in a 4-liter reactor equipped with a reflux condenser, a Celsius-scale thermocouple 11a, a 1-bladed propeller air mixer, and reactor heating (jacket) and cooling (ice bath) equipment. 2550 g of 90% phenol (24.4 moles) were weighed and added to the reactor. 45.6 g of a 45% KOH solution (0.366 mol) were then weighed and added to the reactor. This mixture of phenol and catalyst was stirred while heating to 78 ° C. Meanwhile, 1610 g of 91% flaky paraformaldehyde (48.8 moles) were weighed. After the reactor temperature had risen to 78 ° C, 1/10 (161.0 g) of para formaldehyde flake was added to the reactor. Paraformaldehyde was thus added in a very total of 10 substantially equal increments every 10 minutes. During the addition period, the temperature was maintained between 39,734,45 and about 78-82 ° C. After all the paraform aldehyde was added, the reaction mixture was heated to 85-88 ° C and maintained at this temperature. Bubble viscosities were determined at 25 ° C in a Gardner and Holt bubble viscosity tube (ASTM D-1545-76) from samples of the reaction mixture taken every 30 minutes after the temperature had risen to 85-88 ° C. When the bubble viscosity was obtained for about 15 seconds, the reaction mixture was gradually cooled (about 15 minutes) to about 78 ° C. When this temperature was reached, the bubble viscosities were re-determined every 15 minutes until the viscosity was reached for about 60 seconds. With a bubble viscosity of 60 seconds, 18.7 g of a 90% formic acid solution (0.366 mol) was added to the reactor and the reaction mixture was cooled to 65 ° C. After the reaction mixture was cooled to 65 ° C, 190 g of Morflex 1129 plasticizer (dimethyl isophthalate) was added and allowed to dissolve. The reaction mixture was then transferred to a container and refrigerated until use. The resulting resole had a Brookfield viscosity of 6,000 centipoise at 25 ° C. The resole contained 2.3% free phenol, 3.4% free formaldehyde and 17.5% water. Resol had an average (weight) molecular weight of 902, an average (number) molecular weight of 448 and a degree of dispersion of 2.01.

Example 4

Phenol formaldehyde resole with a molar ratio of formaldehyde to phenol of 2: 1 was prepared on a commercial scale using the recommended method. The reaction was carried out in a 22,700 liter reactor equipped with a reflux condenser, a Celsius scale thermocouple, a precision chemical addition device, a mixture stirrer, and heating and cooling devices for the reaction mixture.

First, 13,755 kg of 90% phenol (131,700.8 gram moles) was charged to the reactor. 256 kg of a 45% KOH solution 40 73445 (1055.8 grams) were then added to the reactor with stirring. This mixture was stirred with heating to 78 ° C. In the meantime, 8701.2 kg of 91% flakes of paraformaldehyde (263,942.7 gram moles) were weighed.

After the reactor temperature had risen to 78 ° C, paraformaldehyde flakes were fed to the reactor at a substantially constant rate over 3 hours. During the addition period, the reactor temperature was maintained between 78 and 82 ° C.

After all of the paraformaldehyde was added, the reaction mixture was heated to 85-88 ° C and maintained at that temperature. Bubble viscosities were determined at 25 ° C in a Gardner and Holt bubble viscosity tube (ASTM D-1546-76) from samples of the reaction mixture taken every 30 minutes after the temperature had risen to between 85 and 88 ° C.

After bubbling viscosity was obtained for about 15 seconds, the reaction mixture was cooled to about 78 ° C. When this temperature was reached, bubble viscosities were determined again every 15 minutes until the viscosity was about 45 seconds. The temperature was then lowered to 68-70 ° C and the bubble viscosities were then determined every 15 minutes until the viscosity was about 60 seconds. After a viscosity of 60 seconds, 94.8 kg of a 90% formic acid solution (1854.8 grams) was added to the reactor and the reaction mixture was cooled to 55 ° C. While cooling the reaction mixture to 55 ° C, 972.5 kg of Morflex 1129 plasticizer was added and allowed to dissolve. The reaction mixture was then transferred to a storage tank and kept refrigerated until use.

The resulting resole had a Brookfield viscosity of 8700 at 25 ° C. The resole contained 3.7% free phenol, 2.92% free formaldehyde and 15.6 S water. Resol had an average (weight) molecular weight of 1480, an average (number) molecular weight of 582 and a dispersion of 2.55.

41 73445

Example 5

A phenolic resole with a molar ratio of formaldehyde to phenol of 2: 1 was prepared in the laboratory by the procedure of Example 3 except that the reaction was stopped, the pH was adjusted, Morflex 1129 was added, and the resole solution was cooled to a bubble viscosity of 10 seconds.

The resulting resole had a Brookfield viscosity of 850 centipoise at 25 ° C. The resole contained 4.1? Ό free phenol, 4.9? О free formaldehyde and 14.0% water. Resol had an average (weight) molecular weight of 519, an average (number) molecular weight of 400, and a degree of dispersion of 1.26.

Example 6

Phenol formaldehyde resole with a molar ratio of formaldehyde to phenol of 2: 1 was prepared in the laboratory in a 4-liter reactor equipped as in Examples 1 and 3. First, 2550 g of 90% phenol (24.4 moles) was added to the reactor. 1610 g of 91% paraformaldehyde were then added to the reactor. This mixture of phenol and formaldehyde was stirred and heated to 70 ° C. While heating the mixture of phenol and formaldehyde, a 45% KOH solution was prepared. As the temperature rose to 70 ° C, potassium hydroxide from 1/6 solution (7.6 g, 0.061 mol) was added. After 10 minutes, another 1/6 portion of KOH solution was added. The remainder of the potassium hydroxide was added in the same manner and the reaction mixture was allowed to heat through exothermic heat evolution under reflux conditions and kept at reflux for 30 minutes. The reaction mixture was then cooled to 78 ° C and allowed to react at this temperature until a bubble viscosity of 80 seconds was obtained. The pH was then adjusted by the addition of 18.7 g (0.366 mol) of 90% formic acid. The phenolic resole solution was then cooled to 65 ° C, 42 7 3 4 4 5 190 g of Morflex plasticizer was added and the solution was further cooled to 55 ° C. The resole solution was then transferred to a container and kept refrigerated until use. The resulting resole had a Brookfield viscosity of 7,500 centipoise at 25 ° C.

The resole contained 2.4% phenol, 3.2% formaldehyde and 15.8% water. Resol had an average (weight) molecular weight of 1055, an average (number) molecular weight of 534 and a degree of dispersion of 1.98.

Example 7

Phenol formaldehyde resole with a molar ratio of formaldehyde to phenol of 2: 1 was prepared in the laboratory using the equipment and general procedure shown in Examples 1 and 3 with the following exceptions.

1434 g of 90% phenol (13.73 moles) were first charged to a 4-liter reactor. Then 1207 g of 91% flakes of parformaldehyde (36.61 moles) were added to the reactor. This mixture of phenol and formaldehyde was stirred and heated to 78 ° C. In the meantime, a 45% KOH solution was prepared, and 35.53 g (0.285 moles) of this 45% KOH solution was added to 478 g of 90% phenol (4.58 moles), and this mixture of potassium hydroxide and phenol was stirred. . This KHH-pheno 1i mixture was then placed in an addition funnel. After the temperature of the mixture of phenol and formaldehyde had risen to 78 ° C, this mixture of KOH-phenol was added dropwise over a period of 150 minutes. The rest of the reaction was carried out in the same manner as in Example 3.

The phenolic resole had a Brookfield viscosity of 6,000 centipoise at 25 ° C. The resole contained 3.2 K phenol, 3.2% formaldehyde and 15.1% water. Resol had an average (weight) molecular weight of 1156, an average (number) molecular weight of 543 and a dispersion of 2.13.

43 73445

Example 8

Phenol formaldehyde resole was prepared in the laboratory as described in Example 3 except that the molar ratio of formaldehyde to phenol was 1.6: 1.

The resulting phenolic resole had a Brookfield viscosity of 6,200 at 25 ° C. The resole contained 1.5% formaldehyde, 3.7% phenol and 16% water. Resol had an average (weight) molecular weight of 1248, an average (weight) molecular weight of 1248, an average (number) molecular weight of 532.6, and a dispersion of 2.36.

Example 9

Phenoformaldehyde reso was prepared in the laboratory as described in Example 3 except that the molar ratio of formaldehyde to phenol was 1.6: 1.

The obtained phenolic resole had a Brookfield viscosity of 6400 at 25 ° C. The resole contained 6.7% formaldehyde, 1.5% phenol and. di8% water. Resol had an average (weight) molecular weight of 1030, an average (number) molecular weight of 561 and a dispersion of 1.85.

Example 10

Phenol formaldehyde resole was prepared in the laboratory following the procedure beginning with line 15 of column 29 of U.S. Patents 4,176,106 and 4,176,216 in connection with resole No. III. The resulting phenolic resole contained 7.3% formaldehyde, 5.6 Å phenol and 7.9% water. Resol had an average (weight) molecular weight of 688, an average (number) molecular weight of 440 and a degree of dispersion of 1.56.

44 7 3 4 4 5

Example 11

According to Example 10, phenol-formaldehyde resole was prepared. After preparing the resole, the water content was adjusted to 16 S. The resole was then heated to 68-70 ° C and maintained at this temperature until a bubble viscosity of 80 seconds was obtained.

The resulting resole contained 5.4 μl of formaldehyde, 2.3% of phenol and 14.8% of water. Resol had an average (weight) molecular weight of 882, an average (number) molecular weight of 515.8 and a degree of dispersion of 1.71.

Example 12 According to Example 17 of U.S. Patent 3,953,645, phenolic resole was prepared.

The resulting resole contained 1.9% formaldehyde, 8.8% phenol and 10.8% water. The average (weight) molecular weight of the phenolic resole was 2295, the average (number) molecular weight was 590 and the degree of dispersion was 3, 8.

Example 13

In the laboratory, phenolic foam was prepared using the laboratory mold shown in Figures IA and IB. The sides of the mold made were 1.3 cm thick aluminum bars, the top and bottom had 0.64 cm thick aluminum plates. The internal dimensions of the mold were 63.5 x 33.0 x 3.1 cm. The dimensions of the mold can be changed, for example, by replacing the 3.1 cm sides with 3.8 cm or 7.6 cm wide bars.

The mold was coated with a mold release agent and preheated in a 66 ° C oven. A dry corrugated piece of paper measuring about 33.0 x 70.1 cm was dried in a 66-inch oven for about 10 to 15 minutes. With the mold and cardboard in the oven, a foamable mixture of phenolic resin was prepared as follows. First, 10 parts (33.2 g) of a 50/50 wt% mixture of Freon 11 / Freon 113 (fluorocarbon blowing agent; trichloromonofluoromethane / 1,1,2-trichloro-1,2,2-trifluoroethane) and 1 part (3.3 g) of a silicone surfactant (Union Carbide L-7003) with a high speed air mixer (3000 rpm). This fluorocarbon hydrogen mixture was placed in an ice bath and cooled to 10.0-18.9 ° C. Using a high speed air mixer, 76.6 parts (2.543 g) of the phenolic resole prepared in Example 1 and 2.4 parts (8.0 g) of silicone surfactant (L-7003) were then mixed. The phenolic resole and surfactant premix were then mixed with the fluorocarbon blowing agent and surfactant premix. This mixture of phenolic resole, blowing agent and surfactant was cooled in an ice bath to 10.0-12.8 ° C. 10 parts (33.2 g) of anhydrous toluenesulfonic acid / xylene acid mixture (ULTRA-TX acid, WITCO Chemical) were then weighed into a syringe and cooled to 4.4-7.2 ° C. The cardboard and mold were removed from the oven. The anhydrous arylsulfonic acid catalyst was then mixed with a mixture of phenolic resole, blowing agent and surfactant at high speed for 10 to 15 seconds. Immediately afterwards, 210 g of a ready-to-foamable mixture of phenolic resole was poured onto the cardboard in the s-shape shown in Fig. 1B. The cardboard was folded over the top of the mixture to be foamed and immediately placed in a mold. The mold was closed, all tensioners were put in place and tightened.

The mold with foamable mixtures was then placed in a 66 ° C oven for 4 minutes. After removal from the oven, the foam was removed from the mold and weighed. The foam was allowed to stand for 24 hours before samples were cut to evaluate the properties of the foam.

The cured foam contained 100% closed cells 46 7 3 4 4 5 as measured by an air pycnometer according to ASTM test D-2856-70. Its density was about 52 kg / m 2. The initial k-value of the foam before equilibration was 0.135. The SEM image of this foam is shown in Figure 6. This SEM indicates that the cell walls of the foam are substantially free of perforations and openings and that the cell walls are thick.

The k-values of the foam during aging are shown in Table I. They also show that the phenolic foam trapped and retained the blowing agent and that the cell walls are thus thick and substantially free of openings or perforations.

Table I

Expiration time k-value 10 days 0.123 30 days 0.122 90 days 0.113 120 days 0.113 280 days 0.118

Example 14

A phenolic resole feed mixture was prepared by mixing 74.6 parts of the phenolic resole prepared in Example 2 and 2.4 parts of L-7003 silicone surfactant.

Anhydrous toluenesulfonic acid / xylenesulfonic acid (ULTRA-TX catalyst, WITCO Chemical) was used as the catalyst.

A phenolic resole feed mixture, a catalyst and a fluorocarbon blowing agent feed mixture containing 6 parts of 1,1,2-trichloro-1,2,2-trifluoroethane, 6 parts of trichloromonofluoromethane and 1 part of L-7003 silicone surfactant were fed separately to the dispenser of the phenolic foam making machine schematically shown in Fig. 2 and mixed there.

47 73445

The phenolic resole feed mixture, catalyst, and blowing agent feed mixture were maintained in the temperature ranges of 9.4 to 12.2 ° C, 0.5 to 2.8 ° C, and -3 to 1.1 ° C, respectively, prior to mixing in the dispenser.

The foamable mixture was applied continuously at a temperature of about 30 ° C for 6 hours to a downward sheet of aluminum-coated paperboard carried by a lower conveyor.

An upward sheet of the same material and polyethylene side papers were fed into the machine just before the curing space, as shown in Figures 2 and 3.

The relative amounts of resole feed, catalyst and blowing agent feed in the foamable mixture were determined eight times during said 6 hours. The results are reported in the following table.

Table II

Time- Elapsed- Resole feed- Catalyst- Blowing agent point total time working mixture, parts ti, parts feed mixture, parts 1. - 15 min. 76 12.8 11.2 2. 45 min. 76 13.0 11.0 3. 61 min. 76 13.0 11.0 4. 101 min. 76 13.8 10.2 5. 170 min. 76 13.6 10.4 6. 255 min. 76 13.8 10.2 7. 315 min. 76 13.8 10.2 8. 360 min. 76 13.8 10.2

The mixture to be foamed was applied to the downward material and the speed of the conveyor was adjusted so that when the foam was expanded to substantially fill the curing space, further expansion was prevented and pressure was built up in the expansion space.

A pressure measurement performed in the expansion space about every 48,734,45 minutes during the run at a distance of about 3/4 from the inlet of the curing space showed that the monometer pressure 2 generated by the foam was in the cavity 0.28 to 0.49 kp / cm. The temperature of the foam just after leaving the curing space was taken four times during the run. They ranged from 72 to 82 ° C.

The foam products were sampled every hour. Table III shows the initial k-values, k-values after aging, and core densities of the foam samples. Figure 7 is a SEM (scanning Electron photomicrograph) image of the phenolic foam prepared in this example. The SEM image clearly shows that there are essentially no cracks, punctures or openings in the cell walls. The k-values in Table III are also an indication of this.

Table III

Sample No. k initial value "k" at 45 days Core density _ _ after (kq / nr) _ 1 0.161 0.118 42.33 2 0.158 0.114 41.54 3 0.164 0.115 45.08 4 0.160 0.114 41.0 5 0.171 0.115 46.0 6 0.168 0.121 44.2 Sample No. 1 was tested after one year. Its k-value was found to still be 0.118.

Example 15

In the laboratory, phenolic foam was prepared in a 0.5 liter (pint) tin can as follows.

First, 10 parts (33.2 g) of a 50/50 wt% mixture of Freon 11 / Freon 113 (fluorocarbon blowing agent; trichloromonofluoromethane / 1,1,2-trichloro-1,2,2-trichloroethane) were mixed. ) and one part (3.3 g) of silicone surfactant (Union Carbide L-7003) with a high speed air mixer (300 rpm). This hydrogen fluoride blowing agent mixture was placed in an ice bath and cooled to 10.0 ° C. 12.8 ° C.

Subsequently, 221 g of the phenolic resole prepared in Example 1 and 2.4 parts (8.0 g) of L-7003 silicone surfactant were mixed in a tin can with a high-speed air mixer 11a. The premix of fluorocarbon blowing agent and surfactant was then mixed with the phenolic resole and surfactant premix.

This mixture of phenolic resole, blowing agent and surfactant was cooled in an ice bath to 10.0-12.8 ° C.

66 g of a 5/3 by weight mixture of phenolsulfonic acid and methanesulfonic acid containing 33% of water were then weighed into a beaker and cooled to 4.4-7.2 ° C. The acid catalyst was then mixed in a jar together with a mixture of phenolic resole, blowing agent and surfactant at high stirring speed for 10-15 minutes. The jar with the foamable mixtures contained therein was placed in an oven at 66 ° C for 4 minutes. After removal from the oven, the foam was allowed to stand for 24 hours before samples were cut to evaluate the properties of the foam.

The foam of this example is shown in Figure 8. The SEM image clearly shows that most of the cell walls have ruptured and that they contain many openings. The SEM image clearly shows how desirable it is to produce a phenolic foam in a substantially closed mold that can withstand the pressure created by the foamable mixture because most of the cell walls of the foam have ruptured. The initial k-value of the foam was about 0.22, which also indicates that the cell walls had ruptured and / or contained openings because no fluorocarbon was left in the foam.

Example 16

In the laboratory, phenolic foam was prepared using the laboratory mold shown in Figures IA and IB. The so-called 73445 mold had 1.3 cm thick aluminum bars on the sides and 0.64 cm thick aluminum plates on the top and bottom plates. Its internal dimensions were 63.5 x 33.0 x 3.1 cm.

The mold was coated with a mold release agent and preheated in a 66 ° C oven. A dry piece of cardboard measuring approximately 33.0 x 71.1 cm was dried in a 66 degree oven for about 10 to 15 minutes. With the mold and cardboard still in the oven, a foamable mixture of phenolic resin was prepared as follows. First, 10 parts (33.2 g) of a 50/50 wt% mixture of Freon 11 / Freon 113 (fluorocarbon blowing agent; trichloromonofluoromethane / 1,1,2-trichloro-1,2,2-trifluoroethane) and one part (3, 3 g) si iconic surfactant (Union Carbide L-5340) at high speed with air mixing (300 rpm).

This fluorocarbon-blowing agent mixture was placed in an ice bath and cooled to 10.0-18.9 ° C. 71.6 parts (237.8 g) of the phenolic resole prepared in Example 3 and 2.4 parts (8.0 g) of L-5340 silicone surfactant and 3 parts (10 g) of urea were then mixed with a high-speed air mixer. The fluorocarbon blowing agent and the surfactant premix were then mixed with the phenolic resole and the surfactant premix.

This mixture of phenolic resole, blowing agent and surfactant was cooled in an ice bath to 10.0-12.8 ° C.

Then, 12 parts (39.8 g) of anhydrous arylsulfonic acid containing 65% by weight of toluenesulfonic acid and 35% by weight of xylenesulfonic acid were weighed into the syringe and cooled to 4.4 to 7.2 ° C. The cardboard and mold were removed from the oven. The anhydrous toluenesulfonic acid / xylenesulfonic acid mixture was then mixed with a mixture of phenolic resole, blowing agent and surfactant at high speed for 10 to 15 seconds. As shown in Fig. 1B, 210 g of a ready-made foamable mixture of phenolic resole was immediately poured onto the cardboard.

The cardboard was folded over the foamable mixture and immediately placed in a mold. The mold was closed and all clamps 51 73445 were placed in place and tightened. The mold with the foamable mixture was placed in a 66 ° C oven for 4 minutes. After removal from the oven, the foam was removed from the mold and weighed. The foam was allowed to stand for 24 hours before samples were cut to determine the properties of the foam.

The cured foam contained 100% closed cells as measured by an air pycnometer according to ASTM test D-2856-70. Its density was about 52 Vq / rr ?. The initial k-value of the foam was 0.14 before equilibration. The SEM image of this foam is shown in Figure 9.

The SEM image clearly shows that the cell walls are thick and do not contain gaps and perforations. This is also evidenced by the k-values, which also indicate that the fluorocarbon blowing agent has remained in the cells.

The following table gives the k-values of the foam as it ages.

Maturation time k-value 10 days 0.117 30 days 0.117 60 days 0.116 90 days 0.114 150 days 0.117

Example 17

A phenolic foam was prepared as described in Example 16 except that the phenolic resole used was the phenolic resole prepared in Example 43.

The SEM image of this foam is shown in Figure 10. The SEM image shows that the cell walls are thick and do not contain 52 to 73445 openings. The initial k-value of this foam was 0.120.

Example 18

A phenolic foam was prepared as described in Example 16 except that the phenolic resole used was the phenolic resole of Example 5.

The SEM image of this foam is shown in Figure 11. The SEM image shows that many cell walls have ruptured and some cell walls are thin and cracked. This example illustrates how necessary it is for the resol to have the molecular weight properties of this invention.

The initial k-value of this foam was 0.22.

Example 19

A phenolic foam was prepared in the same manner as in Example 16 except that the phenolic resole used was the phenolic resole of Example 6.

The SEM image of this foam is shown in Figure 12. The SEM image shows that there are essentially no cracks, punctures or openings in the cell walls. The initial k-value of the foam was 0.138 and after 90 days the k-value was 0.138.

Example 20

A phenolic foam was prepared in the same manner as in Example 16 except that the phenolic resole used was the phenolic resole of Example 7.

The SEM image of this foam is shown in Figure 13. The SEM image shows that the cell walls are substantially free of cracks, punctures and openings. The k-value of the foam after 180 days was 0.118, which clearly indicates that the foam has trapped 53 7 3 4 4 5 blowing agent.

Example 21

A phenolic foam was prepared in the same manner as in Example 16 except that the phenolic resole used was the phenolic resole of Example 8.

The SEM image of this foam is shown in Figure 14. The SEM image shows that many cell walls have ruptured or are thin and cracked. The initial k-value of the foam was 0.22.

Example 22

A phenolic foam was prepared in the same manner as in Example 16 except that the phenolic resole used was the phenolic resole of Example 9.

The SEM image of this foam is shown in Figure 15. The SEM image shows that many cell walls have ruptured. The initial k-value of the foam was 0.206 and the k-value after 30 days was 0.224.

Example 23

A phenolic foam was prepared in the same manner as in Example 16 except that the phenolic resole used was the phenolic resole of Example 10.

The SEM image of this foam is shown in Figure 16. The SEM image shows that many cell walls have ruptured, although foaming was performed in a closed mold that withstood high pressures. This indicates that the molecular weights and dispersibility must be as desired in order to obtain a phenolic foam that does not contain ruptured cell walls. The initial k-value of the foam was 0.22.

54 7 34 4 5

Example 24

A phenolic foam was prepared in the same manner as in Example 16 except that the phenolic resole used was the phenolic resole of Example 11.

The SEM image of this foam is shown in Figure 17. The SEM image shows that the cell walls are substantially free of cracks, punctures and openings. The initial k-value of the foam was 0.127 and the k-value after 30 days was 0.118. This example illustrates that the method of making the resole is not important as long as the required molecular weights and dispersibility are obtained.

Example 25

A phenolic foam was prepared by the method of Example 16 except that the phenolic resole used was the phenolic resole of Example 12.

The SEM image of this foam is shown in Figure 18. The SEM image shows that a large portion of the cell walls have ruptured. The initial k-value of the foam was 0.250. This example shows how important it is to use mainly phenol in the preparation of phenolic resole.

Example 26

Phenolic resole was prepared in the same manner as in Example 2 except that the reaction was stopped when the bubble viscosity was obtained for 80 seconds. This resole contained 15.1% water, 3.1% formaldehyde and 3.2% phenol. This resole had an average (weight) molecular weight of 1504, an average (number) molecular weight of 591 and a dispersibility of 2.55.

A foam was prepared from this resole following the procedure of Example 16.

55 7 3 4 4 5 The SEM image of this foam is shown in Figure 19. The SEM image shows that the cell walls do not contain cracks, punctures or openings. This example shows that the use of preferred resoles is desirable. The initial k-value of this foam was 0.121.

Example 27

In the laboratory, phenolic foam was prepared using the laboratory mold shown in Figures IA and IB. The sides of the mold made were 1.3 cm thick a snow initangos and the top and bottom sides were 0.64 cm thick aluminum ini1. The internal dimensions of the mold were 63.5 x 33.0 x 3.1 cm. The phenolic resole used in this example was a phenolic resole commercially available from Georgia Pacif ie called GP-X - 2014/945.

The water content of this obtained resole was 7% by weight.

In addition, 5% by weight of water was added to give a resole water content of 12% by weight. This resin had an average (weight) molecular weight of 674, an average (number) molecular weight of 398.5 and a dispersibility of 1.69.

The mold was coated with a mold release agent and preheated in a 66 ° C oven. In a 66 degree oven, a dry piece of corrugated cardboard measuring approximately 33.0 x 71.1 cm was dried in about 10 to 15 minutes. While the mold and cardboard were still in the oven, a foamable mixture of phenolic resin was prepared as follows. First, 10 parts (33.2 g) of a 50/50 wt% mixture of Freon 11 / Freon 113 (fluorocarbon blowing agent; trichloromonofluoromethane / 1,2-trichloro-1,2,2-trifluoroethane) and 1 part ( 3.3 g) silicone surfactant (Union Carbide L-7003) with a high speed air mixer (3000 rpm). This fluorocarbon-blowing agent mixture was placed in an ice bath and cooled to 10.0-12.8 ° C. 77.6 parts (254.3 g) of phenolic resole and 2.4 parts (8.0 g) of L-7003 silicone surfactant were then mixed together with a high-speed air mixer. A premix of phenolic resole and surfactant 56: 7 3 4 4 5 was then mixed with the fluorocarbon blowing agent and surfactant. This mixture of phenolic resole, blowing agent and surfactant was cooled in an ice bath to 10.0-12.8 ° C. 10 parts of an anhydrous mixture of toluenesulfonic acid and xylenesulfonic acid (ULTRA-TX acid, WITCO Chemical) were then weighed into the syringe and cooled to 4.4-7.2 ° C. The cardboard and mold were removed from the oven. The anhydrous arylsulfonic acid catalyst was then stirred at high speed for 10 to 15 seconds with a mixture of phenolic resole, blowing agent and surfactant.

Thereafter, 210 g of the finished foamable mixture of phenolic resole was immediately poured onto the cardboard in the s-shaped manner shown in Fig. 1B. The cardboard was folded over the foamable mixture and immediately placed in a mold. The mold was closed, all clamps were put in place and tightened. The mold with foamable mixtures was placed in a 66 ° C oven for 4 minutes. After removal from the oven, the foam was removed from the mold and weighed. The foam was allowed to stand for 24 hours before samples were cut to evaluate the properties of the foam. The k-value of this foam was 0.22. An SEM (scannin Electron photomicrograph) image of this phenolic foam is shown in Figure 20. The SEM image shows that the foam has cell walls with substantially no openings. However, the SEM image also shows that many cells in none of these cells have erupted or are. very thin and contain cracks.

This example demonstrates the need for high molecular weights in accordance with this invention.

Example 28

A phenolic foam was prepared as in Example 15 except that the resole was prepared according to Example 4 and the ratio of ingredients was the same as in Example 17.

The SEM image of this foam is shown at 200x magnification 57 7 3445 in Figure 21 and 400x in Figure 22. These SEM images indicate that the cell walls have ruptured. This example shows that the mold must be substantially closed and withstand the pressures created by the foam mixture to prevent the cell walls from bursting. A comparison of this SEM image with other SEM images, in particular Figures 11, 16 and 20, also shows the difference between a burst caused by a lack of pressure and a burst caused by too much resole when pressure is applied.

Claims (2)

A foamable phenolic resolution mixture for preparing a closed cell phenolic foam comprising an aqueous phenol-formaldehyde resole, a surfactant, a blowing agent and an acid catalyst, characterized in that the molar ratio of phenol-formaldehyde resole to phenol is about 1.7: 1 to 2.375: : 1 -2.25: 1, average (weight) molecular weight greater than about 800, preferably about 950 to 1500, average (number) molecular weight greater than about 350, preferably about 400 to 600, dispersibility greater than about 1, 7, preferably about 1.8 to 2.6, and the content of both free formaldehyde and free phenol is less than 7% by weight, preferably less than 4% by weight. A process for producing a closed-cell phenolic foam having a fluorocarbon blowing agent enclosed in the foam, which process comprises preparing a foamed phenolic resole mixture comprising an aqueous phenol formaldehyde resole, a surfactant, a fluorocarbon blowing agent and an acid catalyst, an acid catalyst, and an acid catalyst. characterized in that the molar ratio of phenol-formaldehyde resole to phenol is about 1.7: 1 to 2.3: 1, preferably 1.75: 1 to 2.25: 1, the average (weight) molecular weight is greater than about 800, preferably about 950 to 1500 , the average (number) molecular weight is greater than about 350, preferably about 400 to 600, the dispersibility is greater than about 1.7, preferably about 1.8 to 2.6, and the content of both free formaldehyde and free phenol is less than 7% by weight, preferably less than 4% by weight.